~ Weekly Newsletter ~

Sydney PC User Group Newsletter 12 - 17 Dec 2016

Sorry for the Newsletter delay -- my personal modem was apparently blitzed by the rumbling thunder last Monday (5/12). I didn't even see any lightning. The modem box said "6000V Lightning Protection". Yeah, right!

New modem to the rescue. All the time I was blaming my long-suffering ISP but a Telstra techo finally proved that a strong DSL signal was indeed reaching my modem. It just didn't recognise it. We should all have hand-held testing instruments like this so we can confirm modem problems.

The Moral:
Whenever storms approach, power down all your computers and modems, disconnect the power cords from wall sockets and then UNPLUG the TELEPHONE LINE too!

Meetings for this week:

Tuesday 13th Dec

Programming: 5:30 pm - 8:00 pm

Come and show your projects, and see some others. We have a computer with a projector, so bring along picture files of your project and we'll project them on the wall. We have a broadband internet connection, so discussion can be wide-ranging. We'll see some new microprocessor applications and programming examples.

Past meetings:
At the November meeting Steve said that small assemblies known as modules are available on the internet for a huge range of electronics and they are often cheaper than buying the individual components. Modules he bought lately include real time clock (RTC)+eeprom, relay+driver transistor+led, DS18B20 temperature sensor and an adjustable DC-DC converter. These were all $2-$3 each and would have cost at least double that to buy the parts individually. His next project will likely include one or more modules mounted onto a base PCB alongside the processor. The only down-side is the 3-4 weeks waiting time for free shipping from China, but if you can wait it is a good deal.

Andrew presented details of a means of controlling a small dc motor by using two PIC12F629 devices. One PIC12 uses short pulses to switch a power FET that applies the full drive voltage to a motor while a second PIC12 modulates this signal in two ways. Firstly it can block the pulses at any time thus allowing a fractional pulse to be applied to stop the motor at a particular position. Secondly it can request an increase in the number of pulses per second. The result is a system that, for a motor that is heavily mechanically loaded, approximates to the way a stepper motor operates in that very slow rotations are possible as well as allowing the motor to run at high speed.

Alex created a barebones Arduino system by burning a bootloader called Optiloader into a standalone ATMEGA328 chip. He used an Arduino Pro Mini to act as an ISP and loaded the Optiloader sketch into it. The Pro Mini was then connected to the ATMEGA328 via the SPI interface and the bootloader burnt into the chip. Finally, the Pro Mini was removed from the circuit and a USB-TTL serial adapter connected to the ATMEGA328 chip. Using the Arduino IDE, sketches can be uploaded to the chip as if it were an Arduino board.

For more details, see


There won't be a Web Design meeting for December.
Please have a great Christmas and see you in the New Year.

Next week's meetings:

  • Tuesday Forum: Tuesday, Dec 20 - 9:30 am - 12:00 noon
  • Family History: Tuesday, Dec 20 - 1:00 pm - 3:00 pm

Tech Tips: